SydneyWater overview

Significant water events

In late March 2011, thunderstorm activity produced intense rainfall in the south of the Sydney region with the coastal and inland area south of Wollongong experiencing over 300 mm over a 4-day period. Rainfall totals observed at Albion Park remained above the 1 in 100-year recurrence level for 4 hours. This contributed to severe flash flooding in the area.

Streamflow

Figures W1 and W2 show streamflow pattern, volumes and variation at two major rivers in the region:

Colo River at Upper Colo in the Hawkesbury–Nepean catchment

Shoalhaven River at Fossickers Flat in the Shoalhaven catchment.

The two river locations were selected for the following reasons:

long-term flow data are available

flows upstream of both river locations are unregulated and diversions are negligible

both are major rivers in terms of flow volumes.

Streamflow in these two rivers mainly varied from average to above average flows throughout the year. Very much above average flows were experienced in the Colo River in January, and the Shoalhaven River in December. This was a result of large volumes of rainfall during November and December. See the
Climate overview for further details of climatic conditions experienced in the region during 2010–11.

Figure W1. Graph of total monthly flow along the Colo River during 2010–11 compared with long-term percentiles

Figure W2. Graph of total monthly flow along the Shoalhaven River during 2010–11 compared with long-term percentiles

Water sharing plans bring water users, still operating under the Water Act 1912 (New South Wales), into the one licensing system managed under the Water Management Act 2000 (New South Wales) and set the rules for how water is allocated for the next ten years.

Once a water sharing plan is approved, the NSW Office of Water (NoW) may establish an implementation program under the Water Management Act 2000 (New South Wales) for relevant areas.

The draft plans for both unregulated river water sources and groundwater sources were on public exhibition from 7 June to 30 July 2010 except for the Kangaroo River water source. The Water Sharing Plan for Greater Metropolitan Region unregulated river water sources and the Water Sharing Plan for the Greater Metropolitan Region groundwater sources both commenced on 1 July 2011 and can be accessed from the NoW website.

In May 2009, the Australian Government announced $77.4 million of funding for the Hawkesbury–Nepean River Recovery Package. The program aims to improve river health by making more water available for environmental flows and reducing nutrient inputs to the river system.

Seven project components are underway which include:

Nutrient smart management

Improving Hawkesbury–Nepean water balance accounting

Irrigation and landscape efficiency project

Licence purchase

Water smart farms

Hawkesbury City Council Windsor effluent reuse system

Nutrient reduction and monitoring.

The program was also responsible for the installation of 800 meters to monitor water extraction. This covers over 95% of licensed volume in the river system.